A Man With Headache, Fever, and Neck Stiffness

A 53-year-old man with a history of pseudogout and receiving immunosuppressives after renal transplant had 2 weeks of stiff neck, headache, and fevers and 3 days of right knee pain and swelling with nuchal rigidity, a positive Kernig sign, no focal neurologic deficits, and a right knee effusion on examination. Blood and CSF cultures were negative, WBC count was high normal, and cervical MRI showed degenerative changes with periodontoid calcifications and reactive marrow. What is the diagnosis and what would you do next?
Source: JAMA - Category: General Medicine Source Type: research